Variable gain amplifier for bar code reader
AssigneeOptoelectronics Co., Ltd.
InventorsMitsuaki Hirono, Naoya Niizeki, Depei Ji
Life of this patent
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Abstract
A system and method for controlling an amplifier in a bar code reader are disclosed, wherein the method may include receiving light at a photodiode within the bar code reader from a bar code being scanned by a scan mirror powered by a scan motor; converting the received light into an initial electrical signal; determining whether the scan motor is undergoing a change in direction; establishing a gain value for the amplifier based on an outcome of the determining step; and amplifying the initial electrical signal into an amplified signal using the established gain value.
Claims13
A system for controlling gain in an amplifier within a bar code reader, the system comprising:
- a scanner for directing light at a bar code, wherein the scanner is configured to scan over the bar code in a first direction and then in a second direction opposite the first direction;
- a photodiode for converting light received at the bar code reader from the bar code into an initial electrical signal;
- an amplifier for producing an amplified signal from the initial electrical signal;
- and
- an amplifier controller for determining a magnitude of the gain used in the amplifier, wherein the determination is based on a scan operation transition signal that is indicative of a change in direction of motion of a scan motor, and wherein the amplifier controller includes:
- (i) an amplitude controller that is configured to receive the scan operation transition signal and to generate an amplitude control signal in response thereto;
- and
- (ii) a motor controller that is configured to transmit the scan operation transition signal to the amplitude controller substantially simultaneously with transmission of a transition control signal from the motor controller to the scan motor.
A method for controlling an amplifier in a bar code reader, the method comprising:
- receiving light at a photodiode within said bar code reader from a bar code being scanned by a scan mirror powered by a scan motor;
- converting the received light into an initial electrical signal;
- determining, based on a scan operation transition signal, whether or not a change in direction of motion of the scan motor has occurred, wherein:
- (i) the scan operation transition signal is transmitted from a motor controller to an amplitude controller, and
- (ii) the scan operation transition signal is transmitted substantially simultaneously with transmission of a transition control signal from the motor controller to the scan motor;
- establishing a gain value for the amplifier based on an outcome of the determining step;
- and
- amplifying the initial electrical signal into an amplified signal using the established gain value.
A method controlling an amplifier in a circuit of a bar code reader, the method comprising:
- coupling a low-level detector and a high-level detector to an output from said amplifier;
- establishing a logical “1” initial value for the low-level detector and a logical “0” initial state for the high-level detector;
- determining whether a first signal indicative of a transition between successive scan operations is high or low, wherein:
- (i) the first signal is transmitted from a motor controller to an amplitude controller, and
- (ii) the first signal is transmitted substantially simultaneously with transmission of a second signal from the motor controller to the scan motor;
- and
- setting a gain value for the amplifier based on values of the low-level detector signal, the high-level detector signal, and the scan operation transition signal.
Dependencies are inferred from the claim text.